多光谱成像技术检验富士施乐C4300彩色激光打印复印一体机形成文件

目的研究富士施乐C4300彩色激光打印复印一体机形成文件的跟踪暗码,对富士施乐C4300彩色激光打印复印一体机形成文件进行识别。方法使用多光谱成像仪对6台富士施乐C4300彩色激光打印复印一体机形成的文件进行观察。结果该6台机器形成文件的跟踪暗码存在特征差异。结论通过跟踪暗码的差异,能够对富士施乐C4300彩色激光打印复印一体机形成文件进行识别。     

利用暗记特征鉴别彩色激光打印、复印文件

目的探讨激光打印机的暗记特征,为鉴别彩色激光打印、复印文件找到一种有效的方法。方法根据不同物质对光的反射特性及蓝色与黄色互补特性的原理,采用420nm左右蓝光照射方法,对部分品牌彩色激光打印、复印文件进行了初步分析研究,总结了暗记点阵形态特征、小点形态特征、出现位置特征和排列含义等特征。结果此方法对彩色激光打印、复印机具的种类鉴别和个体鉴别简便、有效。     

傅立叶变换红外光谱法检验静电复印墨粉

目的　通过对静电复印墨粉进行检验 ,达到对不同厂家及不同型号墨粉区分的目的。方法　首先利用电熨斗加热提取复印件的墨粉 ,然后利用傅立叶变换红外光谱法对 9个墨粉厂家和 2 4种牌号进行检验。结果可以达到厂家区分和大部分牌号区分 ,区分率达到 95 .7%。结论　本研究对实际应用有较大参考价值。     

慎重使用复印的文件检材和样本

随着复印机的普遍使用,文件检验中送检者提供的经复印的文件检材和文件样本也逐渐增多。虽然复印件与文件原件内容一致,大多数复印文件并不失其检验条件,但也不乏因文件经复印发生局部变化而导致检验困难,甚至易使检验结论发生错误。因此,在实际检验中,应慎重地接收使用文件检材或样本的复印件,除非无法获取文件原件者外。这是因为:(1)文件物征的复印件与原件相比,会出现外观上的多种自然改变,干扰鉴定者对文件物证具体特征的掌握、认识甚至造成     

打印复印文件朱墨时序表观特征初探

本文详细介绍了一案例的检验过程,并通过简单实验对激光打印、静电复印形成文件的朱墨时序的表观特征进行了粗浅的探究。总体而言,两种时序在朱墨交叉点的表观特征上具有文字与印文均完整、肉眼感觉文字均压在印文之上的共同点;在两者本质的差异点上,先朱后墨表现为交叉点的墨粉与未交叉部位一致,先墨后朱表现为交叉点的墨粉光泽度增加、具有潮湿感、以及易出现水珠状的印油积聚现象。     

显微共焦激光拉曼光谱仪分析激光打印黑色墨粉字迹

激光打印机是常用办公设备,案件中经常会涉及到激光打印文件的检验,运用显微共焦激光拉曼光谱仪检验激光打印黑色墨粉字迹是一种快速、无损、灵敏度高的检验方法,可以对墨粉成分进行定性分析,在司法实践中,此种方法对激光打印黑色墨粉具有较好的检验效果,应用前景广阔。     

扫描电镜/能谱法检验激光打印文件

目的 应用扫描电镜/能谱法检验不同品牌和型号激光打印机的打印文件,实现对不同机型打印文件的区分。方法 收集不同品牌和型号激光打印机10台,利用扫描电镜/能谱仪对相同的打印字符进行无机元素分析,获得样品的能谱图和mapping分析图,对样品进行定量和半定性分析;同时收集10个不同品牌的A4静电复印纸,分析纸张对实验结果的影响。结果 依据所含元素的种类可以将10台激光打印机分为四类;依据主要元素相对百分含量的比值,对不同品牌和型号激光打印文件进行区分;研究结果表明纸张因素对定性结果影响较小,对定量结果影响较大。结论 扫描电镜/能谱法可以简单、快速、无损的区分和识别激光打印文件,可以应用于二次打印文件的检验,为侦查破案提供线索。     

复印、打印伪造印章印文的特点

当今的社会,科学飞速发展,各种新方法、新技术不断涌现,犯罪分子所采取的新的犯罪手段更是令人防不胜防。日前,我们成功地检验了多起利用打印机伪造印文进行巨额金融诈骗的案件,现就此类伪造印文的特点进行讨论。伪造印文所采用的复印机有全色复印机、双色复印机、单色复印机。伪造印文所采用的打印机是各种类型的激光打印机和喷墨打印机。复印或打印伪造的印文都是将原印文用墨水或墨粉转印到伪造文件上,与真印文相比它们都具有下述特征：（１）图文印迹平实、无抑压盖印痕迹复印或打印的印文是用墨水或墨粉喷涂在纸张表面形成的,纸…     

激光显微共聚焦拉曼光谱仪对红色墨迹的研究

目的利用激光显微共聚焦拉曼光谱仪对文书中常见的红色墨迹材料进行表征,研究该方法对红色墨迹材料的区分能力。方法在785nm激发波长,50倍物镜条件下,对49种红色印文,以及9种彩色喷墨打印和13种彩色激光打印的红色墨迹材料进行拉曼光谱表征。结果通过对71种墨迹样品的谱图进行分析,可以发现,红色印文墨迹、喷墨打印红色墨迹及激光打印红色墨迹的拉曼光谱间均存在差异,同时,拉曼光谱可将这三种墨迹材料分别进一步区分。结论显微共聚焦激光拉曼光谱可对红色墨迹材料进行有效表征和区分。这一方法可对红色印文墨迹进行识别,并且可实现对伪造印文文件的鉴别。     

利用感光鼓损伤印迹确定激光打印件的相对形成时间

目前，司法鉴定中各种有争议的文件物证，往往存在被伪造的可能，其中更换合同中的打印件，在各类民事诉讼案件中出现频率较高，检验难度较大。如何利用无损检验方法揭示文件有无伪造及如何伪造，是鉴定人员面临的问题。本文介绍了利用感光鼓损伤印迹确定激光打印件相对形成时间的一种无损检验的方法。     

Technical Note: Analyzing the effect of repeated fusing on toner to examine printing alterations made by the same laser printer

With continuous innovations in laser printing technology, the number of cases of falsification using laser printers is increasing annually. Difficulties in identifying printing alternations, especially laser-printed alternations by the same printer are increasing. Effectively, repeated printing on the same page by the same printer means the original toner on the document was fused repeatedly. Thus, this study mainly investigates the effects of second fusing on the microscopic morphology of toner to examine whether documents have been tampered with. To detect the influence of fusing on the microscopic morphology of toner, 170 documents printed by 17 different models of laser printers from 5 brands were studied. It was found that, according to microscopic observations, the micrographs of toner may become brighter, darker or both with repetition of the fusing process. By calculating the average gray value of the micrographs of toner, it was found that, in some laser printers, the gray value of the thermoplastic accumulation area will increase after a second fusing, and the gray value of the toner particle dispersion area will decrease. In conclusion, by comparing the micrographs of toner from suspicious and reliable contents on the same page or in the same document, together with the measurement and analysis of average gray values, it is possible to examine the once- and twice-fused document contents, and further determine whether the document has been altered.     

三维立体显微镜在文件检验中的应用

目的通过应用先进的仪器设备,让我们从另一个角度观察文检痕迹特征,寻找到一个文件检验的新视角。方法利用三维立体显微镜,从微观的三维状态下分析文检的痕迹特征(上下位置)。结果能有效区别笔迹书写与印章的先后顺序;打印字迹和印章的先后顺序,同一支笔书写形成的交叉笔划的先后顺序;准确区别打印文书和复印文书等。结论借助三维立体显微镜,能使文件检验水平向前迈进一步。     

常用彩色激光打印机打印文件暗记特征的初步研究

目的收集当前我国常用不同品牌和型号的彩色激光打印机打印样本,研究打印文件上暗记特征的提取分析及其变化规律,探讨彩色激光打印文件暗记特征在鉴定实践中的应用及其在打印文件防伪措施中的价值。方法使用显微镜、文检仪及有关图像处理技术分别检验了彩色激光打印机的打印文件样本。结果彩色激光打印机打印文件上会出现暗记特征,且不同品牌的暗记特征出现规律、形态特征和点阵特征不同。结论暗记特征可作为初步鉴别彩色激光打印机品牌型号及打印时间的依据,具有防伪价值,但其在鉴定实践中还存在一定的局限性,有待进一步研究。     

微束X射线荧光分析法鉴别激光打印机墨粉的研究

目的利用微束X射线荧光分析法（μ-XRF）研究激光打印机用墨粉的鉴别。方法利用μ-XRF对9台不同型号激光打印机用墨粉、对应的打印字迹、提取的字迹墨粉所含元素进行定性、半定量的分析。结果根据检出元素种类的不同,可将9台不同型号激光打印机用墨粉、对应的打印字迹、提取的字迹墨粉分成7类、4类、4类,区分率分别为94.4%、75%、69.4%。结论本研究所建立的μ-XRF鉴别激光打印机墨粉方法具有微区、原位无损检验等优点,对提高激光打印文件检验水平具有现实意义。     

Classification algorithm using halftone features of counterfeit bills and CNN

With recent advancements in image processing and printing technology, home printers have improved in performance and grown more widespread. As such, they have been increasingly used in counterfeiting and forgery. Most counterfeit bills in Korea have been created using home scanners and printers. The identification of printer model is thus necessary to rapidly track down criminals and solve crimes. Household printers can be largely divided into inkjet and laser printers. These two types of printers print halftone textures instead of continuous images. This study proposed a technique of printer classification based on halftone textures that can be observed in printed documents. Since halftone textures are expressed as periodic lattices, the images were transformed via FFT, which is highly effective at expressing periodicity. ResNet, known for its superior gradient flow, was used for training. The experiment was conducted on 12 color laser jets and 2 inkjets. Scans of bills printed by each printer were used, and halftone texture analysis was performed on these images for printer model classification. Each image was cropped into several parts; one of the cropped parts was analyzed. The analysis showed that laser printers could be 100% distinguished from inkjet printers. An accuracy of 98.44% was achieved in make classification. When 50 cropped images were used instead of a single image, the technique achieved 100% accuracy in model classification. The proposed technique is non-destructive; it offers high accessibility and efficiency as it can be performed using a scanner alone, without requiring additional optical equipment.     

On the spectroscopic cum chemometric approach for differentiation and classification of inkjet,laser and photocopier printed documents

The potential of ATR-FTIR spectroscopy combined with chemometric methods is explored for the rapid and no-destructive forensic investigation of inkjet, laser and photocopier printed documents. The aim of the present study is to ascertain the source of origin of unknown printed documents, i.e., whether it belongs to the laser or inkjet or photocopier devices and also to visualize the intra-variations present in the same types of printed documents. It is observed that these printing inks contain polystyrene, bisphenol A, methyl acrylate and aromatic ethers as the main chemical constituents. The standard normal variate normalization is performed in order to eliminate the differences caused by the amount of toner powder/inks. The discrimination among printed documents is achieved by using chemometric methods including hierarchal cluster analysis and principal component analysis. Further, linear discriminant analysis is used to classify the unknown printed documents into its respective class of printing devices. The present methodology provides robust, non-destructive, reproducible, and simultaneous identification methods for printed documents.     

The Examination of Commercial Printing Defects to Assess Common Origin,Batch Variation,and Error Rate*

Abstract: The examination of printing defects, or imperfections, found on printed or copied documents has been recognized as a generally accepted approach for linking questioned documents to a common source. This research paper will highlight the results from two mutually exclusive studies. The first involved the examination and characterization of printing defects found in a controlled production run of 500,000 envelopes bearing text and images. It was concluded that printing defects are random occurrences and that morphological differences can be used to identify variations within the same production batch. The second part incorporated a blind study to assess the error rate of associating randomly selected envelopes from different retail locations to a known source. The examination was based on the comparison of printing defects in the security patterns found in some envelopes. The results demonstrated that it is possible to associate envelopes to a common origin with a 0% error rate.     

测量笔画增宽度判断激光打印文件朱墨时序初探

目的考察印章印文与激光打印字迹交叉部位的笔画增宽现象,得到朱墨时序判断依据。方法制作两种朱墨时序的实验样本,在VSC-6000文检仪下观察,读数显微镜在相同放大倍率测量,记录增宽度,比较同种品牌印文色料在两种时序下笔画的增宽度。结果相同保存条件下同种品牌印文色料不同时序盖印的实验样本都有增宽现象,先墨后朱时序下增宽度较大。结论该方法可以作为朱墨时序判断依据。